Alcohol or drugs breath detecting devices

ABSTRACT

Apparatus for detecting the presence of alcohol in expired breath in the atmosphere, comprising a gas sampler, a detector for the presence of alcohol in a gas sample, an output indicator or recorder coupled to the detector to provide an output signal when alcohol is detected, and an automatic controller for actuating the sampler and detector in response to a signal from a sensor arranged to be responsive to the presence of a subject to be tested.

This invention relates to apparatus for detecting alcohol or drugs inexhaled breath and is particularly applicable in situations where one ormore people are expected to pass or remain in or adjacent a particularposition, or where a person is required to speak into a telephone orradio transmitter for example. This may apply for instance to crowdsentering a football ground, or a railway station, bus station, school,cinema, prison, place of public entertainment, transport, a highsecurity zone, or the like.

The invention may also be applicable to any situation where a subject isrequired to speak into a microphone, for example when using a telephone,or radio transmitter, and can thus be applied to instruments designed tomonitor subjects in "home arrest" or "parole" situations.

In some applications the system must be capable of operating effectivelyto take a large number of tests at short intervals and it is whollyinappropriate to expect each person tested to breath into a breathingtube. Accordingly it is desirable in such applications that theapparatus should be capable of operating at some distance from thesuspect's mouth, but nevertheless it requires some control or indicationof the distance involved in order to provide a reasonably accurate testresult.

Broadly stated from one aspect the invention consists in apparatus fordetecting the presence of alcohol or drugs in expired breath in theatmosphere, comprising a gas sampler, a detector for the presence ofalcohol or drugs in a gas sample, an output indicator or recordercoupled to the detector to provide an output or "drugs" signal whenalcohol or drugs are detected, and an automatic controller for actuatingthe sampler and detector in response to a signal from a sensor arrangedto be responsive to the presence of a subject to be tested.

According to a preferred feature of the invention the sensor isresponsive to speech, or noise level, or fluctuation, or movement,temperature, pressure, mass, body weight, or an interruption in aradiated beam, or a combination of any two or more such "proximity" or"presence" parameters.

Conveniently the sensor includes a microphone responsive to speech at apredetermined acoustic level, and the microphone may be combined withfilters or other circuitry designed to respond to frequency range orpattern or volume of the human voice, and/or to the temperature range ofhuman breath. In a particular preferred arrangement the microphoneproduces a "speech signal" and the apparatus also includes a proximitysensor sensitive to the presence of a human body and producing a"proximity signal" and means for detecting a simultaneous or concurrentcombination of both signals. The proximity sensor may, for example, be atemperature responsive element positioned close to the acoustictransducer, and combined with circuitry designed for example to make thesensor independent of changes in ambient temperature.

In any case the alcohol detector preferably comprises an electrochemicalfuel cell and means for measuring or detecting the output of the cell toprovide an indication of the alcohol content in the sample and the gassampler comprises a pump for drawing or impelling a gas sample,preferably of predetermined volume, into contact with the detector. Thepump is preferably electrically operated and includes a control circuitincorporating a pump, and in order to operate at short intervals the gassampler and detector preferably incorporate a heater and a temperaturecontrol. If the alcohol detector comprises an electrochemical fuel cellit may be desirable to "clear the cell" between tests and to acceleratethis the apparatus may include means for short circuiting the cellbetween tests. Alternatively the cell may be operated on atransresistance amplifier for example, and effectively on continuousshort circuit.

In a particular preferred construction the apparatus includes amicrophone acting as an acoustic transducer sensitive to speech, and anair temperature responsive element located immediately adjacent thereto,the microphone and temperature sensing element being coupled through alogic circuit to the output. Both the microphone and temperature areconveniently located in or adjacent to a cone or cup designed as amicrophone mouthpiece. The temperature sensing element is preferablyincorporated into circuitry designed to sense fluctuations in the outputcaused by air turbulence, and in that way to act as a "proximitysensor".

The apparatus may also include an audible or visible sign or signal tonotify the subject that he should stand closer to the speech detector,this being operated automatically by the proximity detector.

The apparatus may also incorporate a delay device arranged to impose ashort delay on the operation of the breath sampler or pump, to ensurethat optimum breath conditions are achieved before the sample is taken.

The invention may be performed in various ways and one embodiment withsome possible modifications will now be described by way of example withreference to the accompanying drawings, in which:

FIG. 1 is a block diagram illustrating the main components of the firstexample,

FIG. 2 is a block diagram schematically illustrating the triggeringcircuit,

FIG. 3 is a block diagram illustrating the sampling circuit,

FIG. 4 is a block diagram illustrating the cell heating circuit,

FIG. 5 is a block diagram illustrating the "battery low" circuit,

FIG. 6 is a block diagram illustrating the cell voltage measurementcircuit,

FIG. 7 is a block diagram illustrating the resetting logic circuit,

FIG. 8 is a block diagram illustrating another embodiment including amicrophone and thermister proximity detector,

FIG. 9 is a block diagram illustrating the logic components of themicrophone and thermister detector of FIG. 8,

FIG. 10 is a sectional side elevation illustrating the speech conehousing the microphone and thermistor, and

FIG. 11 is a diagram illustrating another embodiment.

The first example is illustrated diagrammatically in FIG. 1 and in thisthe instrument is designed to be installed close to the entry to asports ground or the like and is intended to detect whether entrantshave recently been consuming alcohol in excessive quantities. Itincludes an alcohol detection system combined with a microphone whichwill normally be positioned close to a turnstile or entry gate and soarranged that each entrant must speak closely into the microphone beforebeing admitted. The apparatus includes a speech cone 10 open at thefront end and including a microphone 11 and a gas sampling conduit 12leading to a sampling pump 13 controlled by the sampling circuit 14. Thesampling pump draws in a gas sample and exposes this to anelectrochemical fuel cell 15 whose output is fed to a fuel cellmeasurement circuit 16 and thence after evaluation to a display orwarning indicator 17. A heating circuit 18 is arranged to hold the fuelcell and, if necessary, also the sampling pump system 13 at apreselected temperature. The microphone 11 is electrically coupled tothe trigger circuit 20, which is connected to the resetting logiccircuit 21 which also has an input from the cell measurement circuit 16and output connections to the display circuit 17. A battery low circuit22 indicates a low voltage on the battery and provides an indicationthat the battery needs to be changed.

The triggering circuit to operate the sampling system is illustrated inFIG. 2. As stated it needs to be fully or semi-automatic in operationand it was felt that a delay has to be introduced in the circuit toallow enough breath to accumulate near the microphone for an adequatesample to be taken. In FIG. 2 the microphone 11 is connected through theamplifier 30 to a voltage comparator 31 having an adjustable level setby rheostat 32. The output of this comparator 31 is fed through gate hto a 1.1 second timer 34 providing a delay signal via gate g to NANDgate e and via the inverter f to the set input T of JK flip flop 36which produces the initiating output signal on Q⁻. The trigger may bebypassed by manual switchbutton 37. Thus if at the end of the 1.1 secondtime interval of timer 34 the output of the comparator 31 is still high,the flip flop 36 is set Q⁺ high Q⁻ low.

In this example using an electrochemical fuel cell and a motorized pumpdrawing a sample across the cell enough time must be allowed for thecell output to reach a peak. Accordingly the sampling control circuitillustrated in FIG. 3 includes a cell peak timer 40 and a pump runningtimer 41. The two timers are triggered by the Q⁻ output of the flip flop36 such that the pump motor 42 will then run for 0.9 seconds to draw apredetermined volumetric sample over the cell, the pump speed beingdetermined by an adjustable rheostat 43. During the timing period of thetimer 40 its output on 44 is high so that the relay 45 is energisedthrough transistor switch 46. The relay removes a short circuit 47across the cell 15 (see FIG. 6) thus allowing the cell voltage to beevaluated and after 6.5 seconds the output 44 of the timer goes low, acurrent is pulsed briefly through the comparator 48 and the transistors49, 50 are turned on sounding the buzzer 51. When the voltage acrossresistor 52 falls the transistors are turned off.

In this example it is important to provide heating to theelectrochemical cell and to maintain its temperature. The heater circuitis illustrated in FIG. 4 where the heater 55 is switched on bytransistor 56 under the control of thermistor 57 which is thermallyattached to the same disc which carries the heater 55. As the thermistorbecomes warmer its resistance decreases and this is applied tocomparator 58 to control switch 56 and maintain the heater supply untilthe thermistor's resistance drops. The heater supply then oscillates onand off around this preselected temperature level and resistor 59 actingthrough comparator 60 ensures that LED 61 remains on while the heateroscillates.

The battery voltage check circuit is illustrated in FIG. 5 and is basedon use of a Zener diode 64 as reference, the series resistor 65 beingsuch as to allow enough current flow to hold the diode at correctvoltage. Resistors 66, 67 act as a potential divider and when thevoltage between them falls below the predetermined level comparator 68switch is high and turns on transistor 69 and the LED indicator 70.Hysterisis is provided by the resistors 71, 72.

The cell voltage measurement or evaluation circuit is illustrated inFIG. 6 and one of the problems involved is to allow the cell appropriatetime and conditions to "clear", i.e. to revert to a datum level betweenreadings. The output of the cell 15 is connected to a transresistanceamplifier circuit 75, including amplifier 76, in which its output isconverted to a voltage and fed to the two comparators 77, 78. When thecell output reaches the level set by comparator 77, the output of thatcomparator goes low turning on a transistor 79 to drive a limit LED 80.When the cell output reaches the level determined by comparator 78(which is less than that set by 77) the comparator output at 81 goeslow, is inverted by NAND gate 82 and fed into NAND gate 83. The latteralso receives a signal on S from the cell clear timer (see FIG. 3). As aresult if after 6.5 seconds, as determined by timer 40, the output ofcell 15 has reached a predetermined level the timer 85 will be triggeredand the output of this is fed through the resetting logic circuit ofFIG. 7. As a result the cell 15 is short circuited for at least 24.2seconds before the next sample can be taken.

Referring to FIG. 7 the resetting logic includes NAND gate 86 havingfour inputs, S, θ, C and L of which input C is derived from NAND gate 87connected to the short circuit timer 85. The other inputs are derivedfrom the connections shown in other Figures: S in FIG. 3, θ in FIG. 4 ,and L in FIG. 6. The output of gate 86 only goes low when:

(a) 6.5 second sampling time is up,

(b) The heater is up to temperature,

(c) The cell is not being cleared, and

(d) The cell level is low enough.

When the output of NAND gate 86 goes low the output of NAND gate 90 goeshigh and this is connected to the "clock" pin CK of the JK flip flop 36(see FIG. 2a). The rising edge of clock pulse then sets Q⁻ high and Q⁺low which means that when the input on T from the triggering circuit ishigh the sample can again be taken. The display part of the resettingcircuit is arranged so that when one transistor 91 and hence its LED 92,are on the other transistor 93 and its LED 94 are off. One LED signalsto "Wait" and the other signals "Ready for a Sample".

In the second embodiment illustrated diagramatically in FIG. 8, thesystem includes many of the features of the first embodiment withcertain additions and modifications. In this example there is a speechcone 200 in which is mounted a microphone 201 and a temperature sensingthermistor 202. The microphone output is fed through amplifier 203 anddetector 204 to the AND gate 205, which also receives the signal derivedfrom the thermistor 202 via driver amplifier 206 and detector 207. Thegate output which includes a manual override 209, is fed on 210 to theinput buffer 211 of the basic microprocessor control circuit 212.

The voice cone 200 is also provided with an internal heater 215 operatedand controlled by a thermostatic control unit 216. In addition the voicecone 200 is provided with a small breath sampling inlet 220 leading to asampling system including a sampling pump 221 driven by a small electricmotor 222, the pump being arranged to draw in a breath sample over apredetermined time interval and pass this over an electrochemical fuelcell 224. The cell includes a heater controlled by a thermostaticactuator 226 and the output of the cell is fed through amplifier 227 tothe control circuit 212 and in particular to an analogue to digitalconverter 228. This feeds the output to a central processing unit 213which is also connected to a program memory 214 and a data memory 215.An option select unit 216 controls the functions of the unit 214. Theoutput of the unit 214 is also connected to the output buffer 218, whichhas one output to a warning buzzer 219, another output to a drivercircuit 240 arranged to actuate information or warning signals 241 to244 indicating, for example, "Wait", "Talk Now", "Pass" or "Fail".

The circuitry involved in the components of the voice cone 200 isillustrated in more detail in FIG. 9 in which like parts are indicatedby the same reference numerals. Here the output of the microphone 201 isfed through an adjustable gain band pass filter 199 to the comparatoramplififer 203 and integrator/low pass filter 198 acting as anintegrator to a second comparator 197 whose output is connected to theAND gate 205. The other input to the comparators 203 and 197 is avoltage reference signal 196. The breath temperature sensing thermistor202 is connected across the supply voltage through a constant currentsource 195 and its output is fed through a capacitor 217, which removesthe D.C. component, an adjustable gain rectifier 194, and a low passfilter 193 (which acts in effect as an integrator) to a comparator 192acting as the detector 207 and having another constant voltage referenceinput 191.

The actual construction of the speech cone 10 is illustrated in detailin FIG. 10. The cone 10 in this example is formed of aluminium or otherlight metal and has a mounted flange 180 on its front rim to allow it tobe positioned in an opening or socket of a notice board, the cone havinga central opening at its rear end in which is fitted the microphone 11.The wall of the cone includes a passage 179 acting as a breath samplingentrance leading to the sampling tube 12 and the cone is also providedwith an opening or socket 178 to receive and locate the thermistor 202.Thus it will be seen that when a subject speaks towards the microphone,the speech signal will be processed and fed as one input to the gatecircuit 205. If the subject is sufficiently close to the microphone theresulting turbulence in the local air stream adjacent the thermistor 202will cause fluctuations in the thermistor output which when processed by217, 194 and 193 will be fed as the other input to the gate circuit toact in effect as a "presence signal". It will be noted that thethermistor signal fed to the gate is in this way independent of ambienttemperature and is acting as a turbulence detector rather than an airtemperature sensor.

As mentioned above the invention may also be applied to situations inwhich an individual is required to speak into a microphone and at thesame time to be subjected to a test for alcohol or drugs in the expiredbreath. This may be of particular value, for example, in cases of "homearrest" or "parole", or the like. In essence the subject is required tospeak into a microphone which is coupled via a telephone system or radiotransmitter-receiver link to a remote monitoring unit, and themicrophone is associated with an alcohol or drug detecting system, asdescribed for example in one of the previous embodiments. The output ofthe alcohol detector is fed into the same remote transmission system asthe microphone output so that the remote receiver receives both a speechsignal and an alcohol detection or level signal.

In the system illustrated diagrammatically in FIG. 11 parts similar tocomponents of previous examples are indicated by the same referencenumerals with added suffixes. The apparatus includes a voice cone 200'which incorporates a microphone 201' and heater 215' and has a gassampling inlet 220' and thermistor 202'. The outputs from themicrophone, gas sampler, and thermistor, are incorporated into a controlcircuit 250, which includes most of the components illustrated, forexample, in FIG. 8. In this instance the output of the microphone 201'is also fed to a transmitter unit 251, which additionally has an input252 from the processing circuitry 250, this input 252 carrying a signalwhich indicates or represents the presence or quantity of detectedalcohol in the breath. The transmitter 251, which may be part of atelephone system or, for example, a radio link, is coupled via the linkindicated diagrammatically at 253 to a remote receiver unit 254 which isassociated with a number of filters or identifying circuits 256, 257,258. The filter 256 is arranged to extract or separate from the combinedinput just the information concerning the presence or quantity ofalcohol detected and this is displayed or recorded by the indicator unit260. Filter 257 separates out the speech component of the combinedsignal reaching the receiver 254 and this is fed to a voiceidentification unit 258 containing filters of known type designed toprovide an indication that the frequency pattern of the received speechcomplies with a known pattern previously obtained for that individualsubject. The speech signal is transmitted to the loudspeaker 261 and thereceiving station may also include an associated microphone 262 topermit two-way speech between the two remote stations. As a possiblealternative or addition the system may include an identify cardrecognition unit 264 coupled to the transmitter 251 and an identityrecognition unit 265 at the receiver station to provide an indicationthat the correct card has been inserted.

Thus by means of some or all of these recognition devices, it ispossible for a police officer or other person at the remote station toobtain reasonably accurate information concerning the presence andidentity of the subject speaking into the cone 200' and simultaneouslywith the transmitted speech there is provided a signal representing thealcohol or drug level in the subject's breath.

I claim:
 1. Apparatus for detecting the presence of alcohol in expiredbreath, from a subject, in the atmosphere, comprising a gas sampler, adetector for the presence of alcohol in a gas sample, an outputindicator or recorder coupled to the detector to provide an outputsignal when alcohol is detected, a presence sensor for sensing thepresence of a subject in relation to the gas sampler, and an automaticcontroller for actuating the sampler and detector in response to asignal from a presence sensor.
 2. Apparatus according to claim 1, inwhich the sensor is responsive to noise level, or variation, ormovement, temperature, mass, pressure body weight, or an interruption ina radiated beam, or a combination of two or more such "proximity" or"presence " parameters.
 3. Apparatus according to claim 1 in which thesensor includes a microphone responsive to speech.
 4. Apparatusaccording to claim 1, in which the presence sensor is sensitive tomovement or turbulence in the air adjacent to the sensor.
 5. Apparatusaccording to claim 1, in which the alcohol detector comprises anelectrochemical fuel cell and means for measuring or detecting theoutput of the cell to provide an indication of the alcohol content inthe sample.
 6. Apparatus according to claim 1, in which the gas samplercomprises a pump for drawing or impelling a gas sample into contact withthe detector.
 7. Apparatus according to claim 6, in which the pump iselectrically operated, and including a control circuit incorporating apump running timer.
 8. Apparatus according to claim 1, in which the gassampler and/or detector incorporates a heater and a temperature control.9. Apparatus according to claim 1, in which the detector is anelectrochemical fuel cell.
 10. Apparatus according to claim 9, includingmeans for short circuiting the cell between tests.
 11. Apparatusaccording to claim 9, in which the microphone and temperature detectorare both located in or adjacent to a cone or cup designed as amicrophone mouthpiece.
 12. Apparatus according to claim 1, in which thepresence sensor includes a microphone acting as an acoustic transducersensitive to speech, and a temperature responsive element locatedimmediately adjacent thereto, the microphone and temperature sensingelement being coupled through logic circuitry to the output. 13.Apparatus for detecting the presence of drugs in the expired breath,from a subject, in the atmosphere, comprising a gas sampler, a detectorfor the presence of drugs in a gas sample, an output indicator orrecorder coupled to the detector to provide an output signal when drugsare detected, a presence sensor for sensing the presence of a subject inrelation to the gas sampler, and an automatic controller for actuatingthe sampler and detector in response to a signal from a presence sensor.14. Apparatus for detecting the presence of alcohol in the expiredbreath, from a subject, in the atmosphere, comprising a gas sampler, adetector for the presence of alcohol in a gas sample, an outputindicator or recorder coupled to the detector to provide an outputsignal when alcohol is detected, an acoustic transducer sensitive tospeech and providing a basic speech signal and a proximity or presencesensor sensitive to the presence of an adjacent human body and producinga proximity signal or modulation, and means for detecting a simultaneousor concurrent combination of speech and presence, and an automaticcontroller for actuating the sampler and detector in response to thedetection of the combination of speech and presence.
 15. Apparatusaccording to claim 14, in which the proximity sensor is a temperatureresponsive element positioned close to the acoustic transducer. 16.Apparatus for detecting the presence of drugs in the expired breath,from a subject, in the atmosphere, comprising a gas sampler, a detectorfor the presence of drugs in a gas sample, an output indicator orrecorder coupled to the detector to provide an output signal when drugsare detected, an acoustic transducer sensitive to speech and providing abasic speech signal and a proximity or presence sensor sensitive to thepresence of an adjacent human body and producing a proximity signal ormodulation, and means for detecting a simultaneous or concurrentcombination of speech and presence, and an automatic controller foractuating the sampler and detector in response to the detection of thecombination of speech and presence.
 17. Apparatus according to claim 16,in which the proximity sensor is a temperature responsive elementpositioned close to the acoustic transducer.
 18. Apparatus for detectingthe presence of alcohol in the expired breath, from a subject, in theatmosphere comprising a gas sampler, a detector for the presence ofalcohol in a gas sample, an output indicator or recorder coupled to thedetector to provide an output signal when alcohol is detected, amicrophone responsive to speech and an automatic controller foractuating the sampler and detector in response to the subject's speechbeing detected by the microphone.
 19. Apparatus for detecting thepresence of drugs in the expired breath, from a subject, in theatmosphere comprising a gas sampler, a detector for the presence ofdrugs in a gas sample, an output indicator or recorder coupled to thedetector to provide an output signal when drugs are detected, amicrophone responsive to speech and an automatic controller foractuating the sampler and detector in response to the subject's speechbeing detected by the microphone.